Use of overhead railway lines may help ease traffic in some of China's densely populated cities, according to Wang Mengshu, a professor at the Tunnel and Underground Engineering Research Center at Beijing Jiaotong University.

The professor made the comments via a statement submitted at a press conference held by a Germany-based Air Train International Group (ATI) in Beijing Monday.

The low cost of construction and maintenance of elevated rails also makes them an advantage, Wang said.

Air Train International plans to build 20 to 30 operating sky rails in China within five years, which will utilize Siemens H-Bahn system, a suspended, driverless passenger monorail system.